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The COSMO-LEPS cloud problem over the Alpine region

The COSMO-LEPS cloud problem over the Alpine region. COSMO General Meeting, Moscow, 6-10 September 2010. André Walser MeteoSwiss. Typical summer case…. COSMO-LEPS median COSMO-7 Observations.  many members with a too small diurnal cycle in 2m temperature

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The COSMO-LEPS cloud problem over the Alpine region

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  1. The COSMO-LEPS cloud problem over the Alpine region COSMO General Meeting, Moscow, 6-10 September 2010 André Walser MeteoSwiss

  2. Typical summer case… COSMO-LEPS median COSMO-7 Observations  many members with a too small diurnal cycle in 2m temperature  COSMO-LEPS predicts clearly more clouds than COSMO-7  large spread in deterministic case

  3. SYNOP verif T_2M Europe JJA2010 lead-time +(25-48)h ~1K Observations COSMO-LEPS ensemble mean COSMO-7 00 UTC 00 UTC

  4. SYNOP verif T_2M CH JJA2010 lead-time +(25-48)h ~2K Observations COSMO-LEPS ensemble mean COSMO-7 00 UTC 00 UTC

  5. SYNOP verif CLCT CH JJA2010 20 lead-time +(25-48)h 0 Mean Error COSMO-LEPS ensemble mean COSMO-7 -20 00 UTC 00 UTC

  6. SYNOP verif CLCT Europe JJA2010 COSMO-LEPS ensemble mean of CLCT: Mean error

  7. June 24 case COSMO-LEPS median COSMO-7 Observations

  8. June 24 15 UTC: A sunny day...

  9. June 24 15 UTC:COSMO-LEPS Total cloud cover (CLCT) Low-level cloud cover (CLCL) member 7 member 7

  10. Low level clouds (CLCL)

  11. Low level clouds (CLCL)

  12. Member configuration

  13. Member configuration

  14. COSMO-7 Kain-Fritsch test-suite (1) Impact on CLCT (4 weeks in summer 2010): Tiedtke Kain-Fritsch ~10-15 % higher, but mainly for high cloud cover cases V.Stauch

  15. Observations Tiedtke Kain-Fritsch IFS 00 UTC 00 UTC COSMO-7 Kain-Fritsch test-suite (2) SYNOP verif T_2M Switzerland (lead-time +(01-24)h):

  16. COSMO-7 Kain-Fritsch test-suite (3) • Overestimation of cloud cover for northern Europe (but not for Switzerland) • Impact on diurnal cycle of 2m temperature for Switzerland very small  For entire results see talk about comparison of Tiedtke, Kain-Fritsch and IFS convection schemes in WG3  Results suggest that Kain-Fritsch alone cannot explain the COSMO-LEPS cloud problem

  17. June case: Too moist boundary layer COSMO-LEPS TD_2M and OBS @ Zurich SYNOP station [oC] Kain-Fritsch members Tiedtke members

  18. SYNOP verif TD_2M CH JJA2010 3 0 Mean Error COSMO-LEPS ensemble mean COSMO-7 -3 00 UTC 00 UTC

  19. SYNOP verif TD_2M Europe JJA2010 COSMO-LEPS ensemble mean of TD_2M: Mean error

  20. Soil moisture: typical summer case COSMO-7initial conditions COSMO-LEPS memberinitial conditions [mm] level 1 (0-1cm)  wet Alpine region in COSMO-LEPS

  21. Soil moisture: typical summer case COSMO-7initial conditions COSMO-LEPS memberinitial conditions [mm] level 2 (1-3cm)  wet Alpine region in COSMO-LEPS

  22. Soil moisture: typical summer case COSMO-7initial conditions COSMO-LEPS memberinitial conditions [mm] level 3 (3-9cm)  wet Alpine region in COSMO-LEPS

  23. Soil moisture: typical summer case COSMO-7initial conditions COSMO-LEPS memberinitial conditions [mm] level 4 (9-27cm)  wet Alpine region in COSMO-LEPS

  24. Conclusions • Cloud problem in COSMO-LEPS seems to be caused by Kain-Fritsch together with a too moist boundary layer • Has dramatic impact on 2m temperature • Too moist boundary layer is caused by a too moist soil  Soil merge (COSMO-EU or assimilation cycle) should be introduced as soon as possible • If not possible before spring 2011, skip Kain-Fritsch • When problems with IFS convection scheme are solved ( WG3 talk) consider to use it  Soil moisture should be added to COSMO-LEPS output

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